Recreational pine forests dynamics in "Ozero Shchuchye" nature reserve (St.Petersburg)

Pine forests near Shchuchye Lake in St. Petersburg have been under intensive recreational pressure for more than 60 years. The article presents data on the dynamics of all layers of recreational pine forests resulted from 11 years of observations at two permanent sample plots laid down at the same time as the nature reserve “Ozero Shchuchye” was established. Monitoring of natural complexes was carried out by researchers from Komarov Botanical Institute and St. Petersburg State University in 2011, 2014 and 2022. The study shows that there is a process of self-thinning in the stands (mostly thin pines ( Pinus sylvestris L.) are falling) simultaneously with stock growth and existence of small-leaved tree species. Presence of Picea abies (L.) Karst. reliable undergrowth and its amount gradual increase let us suppose that the role of this species will grow. During the observations the number of shrub layer has increased, mainly due to Sorbus aucuparia . The overall species diversity has increased mainly due to the noticeable influx of ground- and trunk-living bryophytes. In both communities there is an increase in projective cover of boreal vascular species with stable species number at the same time and a reverse situation for forest-edge species (decrease in projective cover simultaneously with increase in species number). Bare soil is gradually overgrown with pioneer vegetation, green mosses and Vaccinium myrtillus . However, communities continue to be at the same stages of recreational disturbance as at the beginning of observations, and no statistically significant changes in the species composition and average projective coverage of ground species have been revealed according to NMDS ordination data over the past period. All this indicates that it takes a longer time to restore vegetation cover in conditions of persistent (although reduced) recreational load.